The present invention relates to a substrate processing apparatus of a single-substrate processing type used in a semiconductor manufacturing process, such as a single-substrate processing type CVD system for forming a thin film on a substrate, or a single-substrate processing type etcher system for thinly removing the surface of a substrate.
A conventional substrate processing apparatus of the type described above is required to carry out processing in a space containing a minimum amount of dust and a minimum number of Na ions, K ions, etc. liberated from the human body and the atmosphere because it is used to form fine electronic circuits on a substrate. To obtain a space containing a minimum number of Na ions, K ions, etc., a conventional substrate processing apparatus comprises a series of chambers as shown in FIGS. 1, 2 and 3.
FIG. 1 is a diagram showing a typical structural example of a conventional substrate processing apparatus for single-substrate processing. In the substrate processing apparatus, first, a gate valve 101 is opened to load a substrate to be processed into a load-unload chamber 102. Upon completion of the loading, the gate valve 101 is closed, and the load-unload chamber 102 is evacuated. A robot chamber 103 is held under a vacuum at all times. After a pressure in the load-unload chamber 102 has reached a predetermined level of vacuum, a gate valve 104 between the load-unload chamber 102 and the robot chamber 103 is opened, and the substrate is taken out of the load-unload chamber 102 and moved into the robot chamber 103 by means of a robot installed in the robot chamber 103.
Thereafter, the gate valve 104 between the robot chamber 103 and the load-unload chamber 102 is closed. Next, a gate valve 106 provided between a processing chamber 105 and the robot chamber 103 is opened. Then, the arm of the robot is extended to load the substrate into the processing chamber 105. A heater (e.g. a lamp heater 108) as a reaction energy source is provided below the substrate 107 loaded into the processing chamber 105. The lamp heater 108 is arranged to face the substrate 107 through a transparent quartz plate 109. The substrate 107 may be placed directly on a resistance heater, as is very often the case. A processing gas supply unit 112 is provided above the substrate 107 to supply a raw material for processing and a carrier gas G toward the substrate 107. The apparatus is further provided with exhaust systems 110 for controlling the pressure in the processing chamber 105. It should be noted that reference numeral 111 denotes a power supply unit for supplying electric power to the lamp heater 108.
FIG. 2 is a diagram showing a structural example of a further improved conventional substrate processing apparatus. In this example, a processing chamber 105 devised to smooth the flow of the raw material and carrier gas G supplied from the processing gas supply unit 112 is provided. When the substrate 107 reaches the processing position as shown, a processing space is formed in the center of the processing chamber 105 by the substrate 107, a smoothly rounded chamber wall and the processing gas supply unit 112. In FIG. 2, reference numeral 113 denotes a bellows, and reference numeral 114 denotes an elevating shaft. The elevating shaft 114 is raised and lowered by an elevating mechanism (not shown) to move the lamp heater 108 and the transparent quartz plate 109 up and down, which are mounted on the upper end of the elevating shaft 114. It should be noted that the gate valves and other members that would adversely affect gas flow and temperature control of the chamber wall are excluded from the processing chamber 105.
FIG. 3 shows an example of further improved conventional substrate processing apparatus. In this apparatus, when the substrate 107 placed on a holder 115 reaches a processing position by means of a holder elevating mechanism 116, the internal space of the processing chamber 105 is separated into two spaces, i.e., a processing space (space A) and a space containing a heat source, a transfer mechanism, etc. (space B). Accordingly, in the space A, a gas flow system can be readily designed primarily taking into consideration processing. Since the space B is isolated from the processing gas, the transparent quartz plate 109 is not subject to fogging and it is, therefore, possible to perform stable heating with the lamp heater 108. Even if a complicated mechanism of the apparatus exists in the space B, since no surface of the mechanism comes into contact with the processing gas, any surface which may generate particles or ions is minimized.
In the above-described examples of a substrate processing apparatus shown in FIGS. 1 to 3, a processing gas supply source of the processing gas supply unit 112 is disposed on the upper side with respect to the substrate 107, and the lamp heater 108 as a heat source is disposed on the lower side with respect to the substrate 107. The advantages and disadvantages of this arrangement will be described below with reference to FIGS. 4 and 5. FIG. 4 shows a structural example in which the processing gas supply source 112 is disposed on the upper side, and the heat source 117 is disposed on the lower side. The advantage of this substrate processing apparatus is that in a gravitational space it is only necessary to place the substrate 107 on a holder, and there is no need to provide a special jig for fixing the substrate 107 on the holder. The disadvantage of this apparatus is that heat convection 118 is generated from the heat source 117 toward the processing gas supply source 112, and it is therefore difficult for the processing gas (reaction precursor) 119 emitted from the processing gas supply source 112 to reach the surface of the substrate 107 smoothly.
FIG. 5 shows a structural example in which the processing gas supply source 112 is disposed on the lower side and the heat source 117 is disposed on the upper side in reverse positional relation to the arrangement shown in FIG. 4. The advantage of this substrate processing apparatus is that since the surface of the substrate 107 to be processed faces downward, there is no likelihood that the surface to be processed will be contaminated with falling particles. The disadvantage of the substrate processing apparatus is that a mechanism is required for turning the substrate 107 upside down and a jig 120 is required for retaining the substrate 107 on a holder. The provision of the substrate retaining jig 120 is particularly disadvantageous from the viewpoint of processing performance because it is located on the processing side.
To solve the above-described problems, there has been proposed a processing chamber structure arranged as shown in FIG. 6. In the illustrated arrangement, the processing gas supply source 112 is disposed on the upper side with respect to the substrate 107, and the heat source 117 is disposed on the lower side with respect to the substrate 107. The substrate 107 is simply placed on the holder 115. With this arrangement, heat convection problems can be solved by rotating the substrate 107 about the center axis thereof. That is, rotating the substrate 107 produces a flow of processing gas 125 flowing from the processing gas supply source 112 toward the substrate 107 and further to the periphery thereof. Thus, the processing gas flow 125 is unaffected by the heat convection and the processing gas is efficiently supplied to the surface of the substrate 107, the processing gas is also thereby efficiently discharged in each sideward direction.
In FIG. 6, reference numeral 115 denotes a holder for holding the substrate 107. The holder 115 is mounted on the top surface of a rotary table 121. The rotary table 121 is rotatably supported on a stationary side 126 via bearings 122. A rotational drive source 123 is provided on the stationary side 126. A rotary target 124 is provided on the outer peripheral surface of the rotary table 121. The rotary table 121 is rotated by a rotating magnetic force transmitted from the rotational drive source 123 to the rotary target 124.
If the substrate processing chamber is arranged as shown in FIG. 6, the above-described advantage, i.e., smooth supply of the processing gas to the surface of the substrate 7 is provided. However, it is necessary in order to replace the rotary table 121, which is a rotary member on which the holder 115 is mounted, to suspend and disassemble the apparatus. To avoid disassembling of the apparatus, the rotary table 121 is designed to have a long working life, and a cleaning operation is carried out to remove deposits from the rotary table without disassembling it. However, deterioration of the apparatus components caused by use of a cleaning gas during the cleaning operation becomes problematic.
It should be noted that substrate processing apparatuses in which a substrate is rotated are disclosed in Japanese Patent Application Unexamined Publication (KOKAI) Nos. 5-152207 and 7-58036. The apparatuses, however, suffer from disadvantages similar to those referred to with regard to the apparatus shown in FIG. 6.
In view of the above-described circumstances, an object of the present invention is to provide a substrate processing apparatus which takes advantage of the arrangement in which a processing gas supply source is disposed on an upper side, and a heat source is disposed on a lower side. The apparatus enables a processing gas to reach the surface of the substrate smoothly by eliminating a problem whereby it is difficult for a processing gas to reach a substrate surface efficiently due to the influence of heat convection. In addition, the apparatus allows replacement of a holder for holding the substrate and a rotary member for supporting the holder without the need for disassembling the substrate processing chamber.
To solve the above-described problems, according to a first aspect of the invention, a substrate processing apparatus is provided which includes a substrate processing chamber, a mechanism for loading and unloading a substrate into and out of the substrate processing chamber, a substrate heating source provided in the chamber, and a raw material supply source for supplying a raw material for processing. During processing of the substrate, the raw material for processing is supplied from a surface facing a surface of the substrate to be processed. When the substrate and a holder on which the substrate is placed are moved to a predetermined position for processing in the substrate processing chamber, the space in the substrate processing chamber is divided by the substrate into an upper space serving as a reaction space for processing and a lower space where the substrate heating source, etc. are placed. The substrate processing apparatus is characterized by including a magnetic force source for holding the holder at the predetermined position in a levitational manner by a magnetic force during processing of the substrate.
In this invention, as stated above, when a substrate is processed in a reaction space where a processing gas is present under a vacuum such as exists in the substrate processing chamber, the substrate is levitated by a magnetic force during processing. Consequently, the apparatus is not subject to particle contamination. In addition, because the holder is held or released according to whether or not there is a magnetic force from the magnetic force source, it becomes easy to perform the operation of holding or releasing the holder, and it also becomes easy to load and unload the substrate into and from the substrate processing chamber. Accordingly, it becomes easy to carry out replacement of the holder and cleaning to remove a deposit on the substrate, etc.
According to a second aspect of the invention, in the substrate processing apparatus according to the first aspect, the holder is rotated about the center axis of the substrate by the magnetic force source.
As stated above, the holder is levitated and rotated by means of the magnetic force source. Consequently, a pumping effect is caused on the surface of the substrate by the rotation of the holder, which allows the flow of processing gas to descend toward the substrate and overcome the ascending current (heat convection) produced by heating. Accordingly, the processing gas reaches the substrate surface smoothly.
According to a third aspect of the invention, in the substrate processing apparatus according to the first or second aspect, the holder is supported by an annular magnetic levitating member. The magnetic levitating member is magnetically coupled to the magnetic force source only when the holder is moved to the predetermined position for processing of the substrate.
As stated above, only when the magnetic levitating member is carried to the predetermined position for processing of the substrate, the magnetic levitating member supporting the holder is magnetically coupled to the magnetic force source. Therefore, when processing is not freely move into or out of the substrate processing chamber. Accordingly, substrate loading-unloading, cleaning and replacement of the holder and the levitating member can all be readily performed.
According to a fourth aspect of the invention, in the substrate processing apparatus according to the third aspect, the magnetic force source includes a magnetic bearing and a rotational drive source, and the magnetic levitating member is supported in a levitational manner by the magnetic bearings and caused to rotate by a magnetic force generated by the rotational drive source.
As stated above, the magnetic levitating member is supported in a levitational manner by the magnetic bearing and rotated by the rotational drive source. Therefore, it is possible to stably perform levitational support control and rotation control of the magnetic levitating member, and even the latter has a large diameter and rotates at a high peripheral speed.
The above and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which preferred embodiments of the present invention are shown by way of illustrative example.